The use of tie-down systems, whether strap type, chain type or other, in the securing and transportation of large loads is well known in the art. Chain type tie-downs are typically utilized on heavy and/or rolling loads, or on loads that can withstand the tie-down tightening process with out undue damage to the goods being secured, such as for securing construction equipment, automobiles, machinery, steel piping, logs and the like. Once the chain is attached to both the object being secured and to the trailer bed, a ratcheting mechanism is the utilized to tighten the chain in order to securely tie the load to the trailer bed. The chain type tie-downs can withstand high tie-down tension with little or no elasticity in the chain itself.
Strap type tie-downs are secured in a manner similar to the chain type tie-downs but are more elastic in nature and tend to elastically stretch when put under tension. This provides a cushioning securing means to the load being secured. The strap type of securing means is more commonly used on crated or boxed loads, or loads that are lighter in weight and required less tension to adequately secure them to a trailer.
With either type of tie-down, a plurality of the chain or strap tie-downs is typically placed over the top of the load to be secured, and then secured to the side edges of the trailer. This secures the load from shifting to either side of the trailer during transportation. Additional chains or straps are used to secure the load to the front and rear of the trailer to prevent the load from sliding forward or backward on the trailer during transportation.
Specific tie-down arrangements for specialized applications have been developed for a variety of reasons and products. U.S. Pat. No. 5,382,123 issued to Dawson on Jan. 17, 1995 provides a device for securing stacked lumber on a trailer for transportation. The device includes a convex shaped element that deforms under tie-down strap pressure so as to provide uniform engagement with the individual elements of lumber on the top surface of the load.
U.S. Pat. No. 4,526,500 to Patrick, issued on Jul. 2, 1995 discloses a protective member for securing metal coils to a trailer utilizing releasable chain or cable retaining means. The protection member lies between the chain or cable and the metal coil in order to prevent damage by the chain or cable to the edges of the metal coil. U.S. Pat. No. 4,770,578 to Coleman, issued Sep. 13, 1988 discloses an arrangement for securing bins to trailers utilizing a tie-down frame.
While these and other tie-down systems are generally effective for their intended purposes, they are inadequate when it comes to securing large construction structures such as pre-stressed or preformed concrete structures. Pre-stressed concrete structures are designed and manufactured to support a vertical load only. If the edges of the top surface of the pre-stressed concrete structure are chipped or damaged in any way, the chipping or damage destroys the integrity of the structure and, as a result, the entire structure must be disposed of as scrap at a loss of tens or hundreds of thousands of dollars plus the cost and disruption to traffic caused by removing the pre-stressed concrete to a disposal site.
Given these concerns, the current method of transporting large construction structures is to lay them on a trailer and allow the friction between the trailer and the weight of the construction structure load to be the primary means of securing the load to the trailer. Chains are utilized only at the front and rear of the trailer and structure in order to try and prevent the structure from sliding forward or backward.
Given a construction structure load can weigh anywhere between 15 to 40 tons or more, the friction does provide some securing means on the load to the trailer. However, every year there are multiple instances, in multiple states, wherein the load loses its frictional resistance to the trailer and falls off of the trailer. The front and rear chains providing little if any real securing means. This results in not only the expensive loss of the structure itself, but the costs to remove the structure and dispose of it. In addition, every year there are instances where people are crushed to death or vehicles are destroyed by the structure falling off of the transport trailers.
Therefore, a need exists to for a more reliable and safer means for securing large construction structures to a trailer for transportation that does not damage the construction structure and better secures the load to the trailer.